By Harvard Medical School
An epidemic of swine flu has recently developed in Mexico and the United States, says the CDC. Swine flu has killed many people, and the outbreak has features that suggest it could become a global pandemic. A pandemic is an epidemic that spreads around the whole world. Pandemics also often cause more severe disease than epidemics.
As of Sunday, April 26, the United States has declared a public health emergency, and suspect or confirmed cases are being reported from many parts of the world. If a pandemic happens, it could be very serious for human health and the global economy (which definitely does not need any more bad news right now). Editor's note: There has been a reported death in the USA as of 4/29/09.
Q: What are "swine flu" and "bird flu"?
A: Flu is a disease caused by the influenza virus. Humans, pigs, birds, and other animals all can be infected by influenza viruses. Typically, influenza viruses can infect only one species, so the influenza viruses of humans are different from those of pigs and birds. However, sometimes a virus can infect more than one species. For example, pigs sometimes can be infected not only with pig influenza viruses, but also with human and bird influenza viruses. Then these viruses can sidle up to one another and swap genes, creating new viruses that have a mix of genes from human, pig, and bird viruses. That is what has happened with this new swine flu virus.
Sometimes this swapping of genes allows a virus that was originally able to infect only pigs or only birds to also infect humans. When that happens, we refer to the illness as "swine flu" or "bird flu." This current virus could actually be called "swine/bird flu," since it has some genes from pig flu viruses and other genes from bird flu viruses. However, for simplicity sake, it is just being referred to as "swine flu."
Q: Are swine flu or bird flu viruses dangerous?
A: Most viruses that cause swine flu or bird flu are very hard to pass from one human to another: they don't cause epidemics. Sometimes, however, further changes in genes create a virus that can spread rapidly among humans, and can produce a more severe illness. One reason this illness is more severe is that the virus is so new. The regular flu that comes each year is caused by a regular human influenza virus that often has similarities to the viruses that have caused the flu in years past, so people have some degree of immunity to the latest virus. The unusual swine flu or bird flu viruses that develop the ability for person-to-person spread are so different that people have little or no immunity to them. That is what some experts worry may be happening with swine flu.
Q: How bad can a global pandemic be?
A: The worst global pandemic in modern times was the influenza pandemic of 1918 to 1919. It affected about a third of the human race, and killed at least 40 million people in less than a year more than have been killed by AIDS in three decades. The world economy went into a deep recession. The average length of life dropped for 10 years. In other words, global pandemics can be a really big deal. On the other hand, other pandemics have been considerably less serious than the 1918 to1919 influenza pandemic.
Q: Can this new swine flu virus be easily transmitted from person to person?
A: Unfortunately, the new swine flu virus can be transmitted between humans. It is not clear yet how easily it is transmitted, nor how it is transmitted. Almost surely it is transmitted by sneezing and coughing, and by skin-to-skin contact (like shaking hands or kissing) with an infected person.
Q: How sick do people get from this virus?
A: Most people infected with the virus have recovered from the illness. In fact, all of the people in the U.S. have recovered.
However, in Mexico, some people have kept getting sicker, and eventually died. The regular flu viruses that come each winter can occasionally cause severe illness and death. Most often, this happens in very young children or frail elderly people. What worries some experts is that many of the deaths in Mexico have been in young, healthy adults. In past pandemics, like the influenza pandemic of 1918 to 1919, it was also young, healthy people who were most likely to die. Experts are puzzled as to why the infection currently appears to be worse in Mexico than in the U.S.
Q: Are there treatments?
A: As of now, the new virus is killed by two antiviral medicines熔seltamivir and zanamivir. Based on experience with other flu viruses, treatment would be most effective if given within 2 days of the onset of symptoms. As long as this current swine flu virus is infecting people, it is likely that health authorities will recommend that people with more severe illness take these medicines.
On the other hand, there is no proven benefit from using the medicines before symptoms develop, and there is proven harm: unnecessary widespread use of these drugs could produce drug-resistant viruses.
There is no vaccine yet for the new virus, and the Centers for Disease Control and Prevention (CDC) has expressed doubt that this year's regular flu vaccine will offer protection.
Q: How do I know if I've caught swine flu?
A: The initial symptoms of this flu virus are like those of the regular, annual flu viruses: fever, muscle aches, runny nose, and sore throat. Nausea, vomiting, and diarrhea may be more common with this swine flu than with the regular flu. If this epidemic hits your community and you develop flu-like symptoms, it is likely your doctor will take samples from your throat or material you cough up and send them to the state public health laboratory for testing.
Q: How do I protect myself?
A: To protect yourself from catching swine flu, take the same steps you would to prevent getting any cold or flu:
- Wash your hands or use alcohol-based hand cleaners frequently.
- When you greet people, don't shake hands or exchange kisses.
- Avoid contact with people with flu symptoms.
Q: How long are people contagious?
A: Adults should be considered contagious until at least 7 days after the start of symptoms; with children, it may be 10 to 14 days.
Q: Can you get swine flu from eating pork?
A: Absolutely not. But, as you probably know, you need to cook pork thoroughly to avoid getting other illnesses that can be spread by undercooked meat.
Q: Will there be unusual restrictions on our lives if there is a global pandemic?
A: If there is a global pandemic, for some period of time, governments may well restrict travel (indeed, some governments already have). Governments also may close schools and public places, require as many people as possible to work from home, tell any people who develop symptoms to isolate themselves at home, and tell people to seek medical attention immediately if more serious symptoms develop. What are those symptoms?
For adults, teens, and kids age 3 to 12, the most worrisome symptoms are:
- Shortness of breath
- Persistent vomiting
- Confusion
- Dizziness
- Very rapid breathing
- Not interacting normally, not eating or drinking normally, being unusually irritable, or appearing unusually sleepy
- High fever and rash
- A bluish color of the lips and skin
To purchase the full Special Health Report on swine flu from Harvard Health Publications, click here.
Copyright ｩ 2009 by Harvard University. All rights reserved
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